The goal of the research described in this proposal is to advance our understanding of fundamental biological mechanisms used to construct auditory and other mechanosensory systems. The experiments proposed here have two objectives. First, we plan to develop techniques that will be generally applicable to the investigation of auditory systems from insects to mammals. Second, we will use these techniques to study development and differentiation of the Drosophila (fruitfly) auditory organ. Together these experiments will expand the utility of Drosophila as a model for hearing research while providing insight into the differentiation and function of the Drosophila auditory organ. The experiments are focused the cut gene. We have shown that cut mutants are deaf and that their deafness is correlated both with defects in the mechanotransducing structures of the auditory organ and with neurodegeneration. The approaches used to date have provided only a partial picture of cut function with little insight into specific mechanisms of cut action. Here, I propose to develop and utilize an innovative and powerful combination of chromatin immunoprecipitation (ChIP) and microarray expression analysis to identify genes regulated by Cut.cut encodes an unusual homeodomain transcription factor whose human homolog, CCAAT-displacement protein (CDP)/CUTL1, has been implicated in cell cycle regulation and functions as a tumor suppressor. The proposed experiments will significantly expand our understanding of what Cut/CDP proteins do and how they do it. Fields that will be substantially impacted by these studies include: hearing, mechanosensation in general, Cut/CDP biology, and transcription factor biology. In light of the emerging developmental genetic parallels between Drosophila and vertebrate auditory organ development, I anticipate that information generated by the proposed experiments also will be relevant to human hearing.